Japanese Unexamined Patent Application Publication No. S60-132103 discloses an actuator for use in robots having an elastic tube, or an enclosure made of hollow flexible rubber, and a tubular network covering an outside of the enclosure. This actuator is used for swinging, for example, a pin-connected arm member. Additionally, an actuator having a plurality of artificial muscles that are bundled together has been developed and assembled for nursing care devices, rehabilitation devices, and the like.
Japanese Unexamined Patent Application Publication No. H03-028507 discloses a bendable actuator having a plurality of tubular members. Each tubular member has a hollow elastic extensible member made of rubber or the like, and a braided structure that encloses the elastic extensible member. The braided structure is formed by polyester fibers, the elastic extensible member has a closure member fixed in each end portion, and the closure member is provided with a connecting aperture that communicates with the inside of the elastic extensible member. Japanese Unexamined Patent Application Publication No. 2010-279689 discloses an artificial muscle member comprising: an expansion body formed by a rubber tube surrounded by a braided lace, and a contraction body formed by another braided lace; an outer peripheral length of the braided lace of the contraction body is shorter than an outer peripheral length of the braided lace of the expansion body. The rubber tubes that are used for the expansion body are circular or star-shaped in their cross-sections, and strings made of polyester are used for each braided lace.